Ghosts of the past

With all the new technology in the world,  it is hard to get away from the past.  Facebook, twitter, blogs, myspace... hard to forget with all the ways to be sucked back into it.  Why is it that high school could be such a dreary time in most people's life, but they will add people from that time as "friends" on facebook.   I know I could simply ignore them or block them, but I feel bad on some level, like I should be nice to some of the people that were less than nice to me.  There are times when it is great to touch base with actual friends, people who you did hang out with and simply lost track of over time. But the ones that were less than nice, or the relationship ended on a bad note, those are the ones that I think about later and wonder "why did I accept their friendship?" Is there a point in time where you should just forgive and forget when it comes to the past. I am the type of person to play things over and over again in my head. I think that some how if  I would have reacted differently, that it would have been a better/different/final outcome.  If I were to say, "block" the new friend, would that say something about me and how I feel about my past?  Or would it simply say that I am still living in high school?  And let me give the disclaimer that my life, as with most peoples, is FAR better now than it was way back when. I have a loving husband, a great dog and a wonderful life. I wouldn't change anything for what I have now.   I just sometime wonder if it wouldn't be better if the ghosts of the past would seriously just stay there.